Speed Converter

How speed conversion works

Everyday speed is quoted in mph or km/h, science uses meters per second, and aviation and shipping use knots. The knot is based on the nautical mile — one minute of latitude — which is why 1 knot is exactly 1.852 km/h.

All speed conversions

Every speed pair has its own quick-reference page with a conversion table:

Back to the full unit converter for all seven categories.

Common mistakes to avoid

• Mixing up ounces. The Weight category uses the ounce (oz), a unit of mass (28.3495 g). The Volume category uses the US fluid ounce (fl oz), a unit of capacity (29.5735 mL). One fluid ounce of water weighs about 1.04 oz, not exactly 1 oz, so always confirm which category you are in before converting.
• Confusing bits and bytes. File sizes are measured in bytes, network speeds in bits. In Data storage, 1 byte equals 8 bits, so a 100 Mbit per second connection transfers at most 12.5 megabytes per second.
• Assuming imperial gallons. Every volume unit here is US customary: 1 US gallon is 3.785 liters. A UK imperial gallon is 4.546 liters, roughly 20 percent larger, so results will not match UK fuel economy figures.

A quick accuracy check

Want to sanity-check any converter? Convert -40 from Celsius to Fahrenheit: the result must be exactly -40, the only temperature where the two scales meet. Then convert 0 Kelvin to Celsius: you should get -273.15, absolute zero. A converter that handles both edge cases correctly has sound temperature formulas, and this one does.

Frequently asked questions